<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body{
            background: silver;
            color: blue;
        }
        hr{
            color: red;
        }
    </style>
</head>
<body>
<h2>二号标题</h2>
<hr>
现在我们讲授的是<span style="color: green; background: orange">CSS</span>，<span style="color: green; background: orange">CSS</span>是层叠样式表。
</body>
</html>